1. Technical Field
The present invention relates to an aqueous resin composition, particularly an aqueous resin composition which is useful for coatings, primers, adhesives, printing ink, and the like.
2. Background Art
A polyolefin chloride resin has excellent adhesion particularly to polyolefin resins, such as polypropylene and ethylene-propylene copolymers, and further has excellent solvent-resistance. So the polyolefin chloride resin is widely used for the purpose of protecting surfaces of plastics. Conventional methods for coating the polyolefin chloride resin include using a coating solution in which a polyolefin chloride is dissolved in an organic solvent. However, considering environmental influence, working environment, safety, and so on, there have recently been proposed polyolefin chloride-containing water dispersions in which polyolefin chloride-containing resins are dispersed in water. Japanese Official Patent Provisional Publication (Kokai) No. Heisei 1-245041 discloses an aqueous composition including an alkenylbenzene polymer and a polyolefin chloride. This aqueous composition is obtained by forcibly dispersing the polyolefin chloride into an aqueous medium, in which the alkenylbenzene polymer is dispersed, or by polymerizing the alkenylbenzene polymer and the like in an aqueous medium in the presence of the polyolefin chloride. In addition, Japanese Official Patent Provisional Publication (Kokai) No. Heisei 1-272670 discloses an aqueous composition including a carboxyl group-containing resin composition and a polyolefin chloride.
As to the aqueous composition disclosed in Japanese Official Patent Provisional Publication (Kokai) No. Heisei 1-272670, because of the use of the carboxyl group-containing resin composition, the dispersibility of the polyolefin chloride in the aqueous composition is improved when compared with that disclosed in Japanese Official Patent Provisional Publication (Kokai) No. Heisei 1-245041. However, any coating film obtained from these aqueous compositions provides poor results with regard to adhesion, water resistance, and solvent resistance, so these aqueous compositions are only utilized for limited uses.
In technical fields different from that which an aqueous composition containing a polyolefin chloride pertains to, it is known that a composition containing an acrylic resin or an urethane resin is used to improve the adhesion with substrates. For example, Japanese Official Patent Gazette (Kokoku) No. Showa 63-48884 discloses that an acrylic resin having a carboxyl group and a polymer containing an oxazoline are used. Japanese Official Patent Gazette (Kokoku) No. Heisei 6-39548 discloses that an urethane resin having a carboxyi group and a polymer containing an oxazoline are used. However, there is a problem that, even if these compositions are coated on substrates including polyolefin resins, the adhesion is not sufficient.